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Security: Prevent zip slip during archive extraction #5112

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13924d6
Security: Prevent zip slip during archive extraction
cursoragent Jun 3, 2026
71416be
Address CodeRabbit review: isolate zip extraction from Django imports.
RishabhJain2018 Jun 6, 2026
fec47a3
Address CodeRabbit review: validate YAML-derived paths under extracti…
RishabhJain2018 Jun 14, 2026
ea6291e
Merge branch 'master' into cursor/fix-zip-slip-extraction-9812
RishabhJain2018 Jun 14, 2026
05ae194
Potential fix for pull request finding 'Empty except'
RishabhJain2018 Jun 14, 2026
e560df1
Merge branch 'master' into cursor/fix-zip-slip-extraction-9812
RishabhJain2018 Jun 14, 2026
99b0117
Address remaining CodeRabbit review on zip path hardening.
RishabhJain2018 Jun 14, 2026
a1e5611
Fix unit tests for zip path hardening changes.
RishabhJain2018 Jun 14, 2026
4c93dc0
Add tests for zip path traversal coverage gaps.
RishabhJain2018 Jun 14, 2026
a61e500
Merge branch 'master' into cursor/fix-zip-slip-extraction-9812
RishabhJain2018 Jun 15, 2026
2966897
Fix UnboundLocalError when test annotation path is unsafe.
RishabhJain2018 Jun 15, 2026
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34 changes: 34 additions & 0 deletions apps/base/zip_utils.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
import os
import zipfile


class PathTraversalError(ValueError):
"""Raised when a resolved path escapes its intended root directory."""


def safe_join_under_root(root, *relative_paths):
"""
Join path segments under root and verify the result stays within root.
"""
root_path = os.path.abspath(root)
candidate = os.path.abspath(os.path.join(root_path, *relative_paths))
if not (
candidate == root_path or candidate.startswith(root_path + os.sep)
):
raise PathTraversalError("Path escapes extraction root.")
return candidate
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def safe_extract_zip_file(zip_ref, destination):
"""
Extract zip archive members while preventing path traversal (zip slip).
"""
destination_path = os.path.abspath(destination)
for member in zip_ref.namelist():
member_path = os.path.abspath(os.path.join(destination_path, member))
if not (
member_path == destination_path
or member_path.startswith(destination_path + os.sep)
):
raise zipfile.BadZipFile("Zip archive contains unsafe file paths.")
zip_ref.extractall(destination_path)
135 changes: 86 additions & 49 deletions apps/challenges/challenge_config_utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,11 @@

import requests
import yaml
from base.zip_utils import (
PathTraversalError,
safe_extract_zip_file,
safe_join_under_root,
)
from challenges.models import (
Challenge,
ChallengePhase,
Expand Down Expand Up @@ -95,9 +100,11 @@ def write_file(output_path, mode, file_content):

def extract_zip_file(file_path, mode, output_path):
zip_ref = zipfile.ZipFile(file_path, mode)
zip_ref.extractall(output_path)
logger.info("Zip file extracted to {}".format(output_path))
zip_ref.close()
try:
safe_extract_zip_file(zip_ref, output_path)
logger.info("Zip file extracted to {}".format(output_path))
finally:
zip_ref.close()
return zip_ref
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Expand Down Expand Up @@ -172,10 +179,15 @@ def is_challenge_config_yaml_html_field_valid(
is_valid {boolean} -- flag for field validation is success
message {string} -- error message if any
"""
value = join(base_location, yaml_file_data.get(key))
relative_path = yaml_file_data.get(key)
message = ""
is_valid = False
if value:
if relative_path:
try:
value = safe_join_under_root(base_location, relative_path)
except PathTraversalError:
message = "Invalid file path for {}.".format(key)
return is_valid, message
if not isfile(value):
message = "File at path {} not found. Please specify a valid file path".format(
key
Expand Down Expand Up @@ -293,7 +305,13 @@ def is_challenge_phase_split_mapping_valid(


def get_value_from_field(data, base_location, field_name):
file_path = join(base_location, data.get(field_name))
relative_path = data.get(field_name)
if not relative_path:
return None
try:
file_path = safe_join_under_root(base_location, relative_path)
except PathTraversalError:
return None
field_value = None
if file_path.endswith(".html") and isfile(file_path):
field_value = get_file_content(file_path, "rb").decode("utf-8")
Expand Down Expand Up @@ -464,8 +482,9 @@ def read_and_validate_yaml(self):

# YAML Read Error
try:
self.yaml_file_path = join(
self.base_location, self.unique_folder_name, self.yaml_file
self.yaml_file_path = safe_join_under_root(
join(self.base_location, self.unique_folder_name),
self.yaml_file,
)
self.yaml_file_data = read_yaml_file(self.yaml_file_path, "r")
return True
Expand All @@ -480,6 +499,10 @@ def read_and_validate_yaml(self):
).format(error_description, line_number, column_number)
self.error_messages.append(message)
return False
except PathTraversalError:
message = "Challenge configuration contains unsafe file paths."
self.error_messages.append(message)
return False

def _approved_config_locked(self):
return (
Expand Down Expand Up @@ -612,19 +635,18 @@ def validate_challenge_logo(self):
or image.endswith(".jpeg")
or image.endswith(".png")
):
self.challenge_image_path = join(
self.base_location,
self.unique_folder_name,
self.extracted_folder_name,
image,
)

if isfile(self.challenge_image_path):
self.challenge_image_file = ContentFile(
get_file_content(self.challenge_image_path, "rb"), image
self.challenge_image_file = None
try:
self.challenge_image_path = safe_join_under_root(
self.challenge_config_location, image
)
else:
self.challenge_image_file = None
if isfile(self.challenge_image_path):
self.challenge_image_file = ContentFile(
get_file_content(self.challenge_image_path, "rb"),
image,
)
except PathTraversalError:
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Fixed
pass
else:
self.challenge_image_file = None
self.files["challenge_image_file"] = self.challenge_image_file
Expand Down Expand Up @@ -737,26 +759,33 @@ def validate_evaluation_script_file(self):
)
self.error_messages.append(message)
else:
evaluation_script_path = join(
self.challenge_config_location, evaluation_script
)
# Check for evaluation script file in extracted zip folder
if isfile(evaluation_script_path):
self.challenge_evaluation_script_file = (
read_file_data_as_content_file(
evaluation_script_path,
"rb",
evaluation_script_path,
)
)
self.files["challenge_evaluation_script_file"] = (
self.challenge_evaluation_script_file
try:
evaluation_script_path = safe_join_under_root(
self.challenge_config_location, evaluation_script
)
else:
except PathTraversalError:
message = self.error_messages_dict.get(
"missing_evaluation_script"
)
self.error_messages.append(message)
else:
# Check for evaluation script file in extracted zip folder
if isfile(evaluation_script_path):
self.challenge_evaluation_script_file = (
read_file_data_as_content_file(
evaluation_script_path,
"rb",
evaluation_script_path,
)
)
self.files["challenge_evaluation_script_file"] = (
self.challenge_evaluation_script_file
)
else:
message = self.error_messages_dict.get(
"missing_evaluation_script"
)
self.error_messages.append(message)
else:
message = self.error_messages_dict.get(
"missing_evaluation_script_key"
Expand Down Expand Up @@ -900,25 +929,33 @@ def validate_challenge_phases(self, current_phase_config_ids):
self.error_messages.append(message)
test_annotation_file = data.get("test_annotation_file")
if test_annotation_file:
test_annotation_file_path = join(
self.challenge_config_location, test_annotation_file
)
if isfile(test_annotation_file_path):
challenge_test_annotation_file = (
read_file_data_as_content_file(
test_annotation_file_path,
"rb",
test_annotation_file_path,
)
)
self.files["challenge_test_annotation_files"].append(
challenge_test_annotation_file
try:
test_annotation_file_path = safe_join_under_root(
self.challenge_config_location, test_annotation_file
)
else:
except PathTraversalError:
message = self.error_messages_dict[
"no_test_annotation_file_found"
].format(data["name"])
self.error_messages.append(message)
self.files["challenge_test_annotation_files"].append(None)
else:
if isfile(test_annotation_file_path):
challenge_test_annotation_file = (
read_file_data_as_content_file(
test_annotation_file_path,
"rb",
test_annotation_file_path,
)
)
self.files["challenge_test_annotation_files"].append(
challenge_test_annotation_file
)
else:
message = self.error_messages_dict[
"no_test_annotation_file_found"
].format(data["name"])
self.error_messages.append(message)
else:
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test_annotation_file_path = None
self.files["challenge_test_annotation_files"].append(None)
Expand Down
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